1. Field of the Invention
This invention generally relates to shortening systems and finds special application in confectionary shortenings such as those incorporated into icings and cake batters. More particularly, the invention is directed to shortening systems having a fat component which is selectively hydrogenated so as to exhibit a very low level of trans-stereoisomers. The shortening systems can include an emulsifier of a polyglycerol ester type.
2. Description of Related Art
An important consideration for some shortenings, and especially confectionary shortenings, is that they may be hydrogenated so that the melting point of the fat is high enough to avoid running or bleeding or melting at temperatures so low that handling is made difficult or the food becomes sticky. In many shortening or fat system applications, hydrogenation is required in order to provide fats or shortenings that exhibit needed physical properties, especially at differing temperatures at which the products are intended to be used.
One present concern regarding hydrogenated fats is that most hydrogenation approaches result in a relatively high trans-stereoisomer content. In some circles, there is a concern that trans-isomers pose a health risk not associated with hydrogenation per se, but with the presence of substantial trans-stereoisomer configuration content within the hydrogenated fat. Accordingly, if one wishes to minimize the presence of trans-isomers in confectionary products, hydrogenation should be limited. Yet, limited hydrogenation often will not provide the melt characteristics and mouth feel needed for confectionary systems.
Scavone U.S. Pat. No. 5,470,598, which is incorporated by reference hereinto, describes all-purpose shortening which is said to have reduced levels of trans fatty acids. This is achieved largely by incorporating base oils having very low trans fatty isomers in combination with certain beta-prime hard stock comprising a combination of a triglyceride of palmitic and stearic acid with a particular configuration of stearyl and palmityl groups, together with a triglyceride of palmitic and stearic acid with palmitic and stearic acid groups occupying certain positions. Requiring these types of sophisticated fat structures is not a suitable solution for most high-volume applications. This patent also suggests incorporating beta prime compatible emulsifiers including polyglycerol esters of fatty acids having fatty acids of 12 to 22 carbon chain lengths.
Roberts et al. U.S. Pat. No. 6,033,703, incorporated by reference hereinto, also relates to all-purpose shortening having reduced levels of trans fatty acids. This is said to be accomplished with an edible oil having very low levels of trans fatty acids combined with a hard stock blend of beta prime phase tending hard stock components, together with an emulsifier, while including inert gas injection during processing.
Harrod et al. U.S. Pat. No. 6,265,596, incorporated by reference hereinto, teaches partially hydrogenating fats which have a low content of trans fatty acids. The approach of this patent is to combine the fat, hydrogen gas and a solvent which dissolves the fat and the product as much as possible. This is called a super-critical process and is carried out in the presence of a palladium catalyst or a nickel catalyst. A typical solvent for this approach is a hydrocarbon such as propane.
Chrysam et al. U.S. Pat. No. 6,022,577, incorporated by reference hereinto, relates to fat products which can have low trans content. An interesterified blend is practiced, such as a random interesterification of a hysteric stearic acid soybean oil blend.
Hasman U.S. Pat. No. 4,134,905, incorporated hereinto by reference, discloses a time-consuming two-step approach for preparing trans acid restricted hard butters. The first step is hydrogenating with copper-chromite catalyst, with the second step being hydrogenation with a more-conventional catalyst, typically a nickel catalyst.
Chaen U.S. Pat. No. 4,161,483, incorporated by reference hereinto, describes a hydrogenation process which is said to reduce the formation of trans-isomers and/or conjugated dienes and/or saturated compounds. This proposes carrying out the hydrogenation in the presence of a nickel catalyst and an organic nitrogen-containing basic compound such as urea, hexamethylenetetramine and aliphatic amines.
Villagran et al. U.S. Pat. Nos. 6,228,414, 6,395,323 and 6,436,459 relate to low-fat snacks which incorporate a variety of polyglycerol ester compounds as emulsifiers in low-fat snack compositions. The subject matter of each of these patents is incorporated by reference hereinto.
These various approaches have limited applicability in achieving efficient hydrogenation of commodity-type fat sources while forming minimum levels of trans-stereoisomers. Many are expensive and/or difficult to manage in large-scale industrial production contexts. Nor is there a teaching of emulsifiers which are especially suitable for low-trans confectionary shortening systems.